[pulseaudio-discuss] can rewindings in the null sink produce noises in programs recording its monitor?

[wellington wallace]

>
>
> >* Hi! PulseEffects developer here again.
> *> >* Like the title says I'd like to know if rewinds can cause crackling noises
> *>* when we are recording from a null sink monitor.
> *
> Yes it can: https://gitlab.freedesktop.org/pulseaudio/pulseaudio/issues/304
>
> >* In PulseEffecs I use the
> *>* plugin pulsesrc from GStreamer to record the null sink monitor and whenever
> *>* there is a change in the null sink volume or in the volume of a sink input
> *>* playing to the null sink I can here noises. Looking at Pulseaudio's logs I
> *>* can see lines with:
> *> >* [null-sink] module-null-sink.c: Requested to rewind 3528 bytes.
> *>* [null-sink] sink.c: Processing rewind...
> *>* [null-sink] sink-input.c: Have to rewind 2840 bytes on render memblockq.
> *>* [null-sink] sink-input.c: Have to rewind 1420 bytes on implementor.
> *>* [null-sink] source.c: Processing rewind...
> *>* [null-sink] module-null-sink.c: Rewound 2840 bytes.
> *>* [pulseaudio] module-stream-restore.c: Storing volume/mute/device for stream
> *>* sink-input-by-media-role:music.
> *>* [pulseaudio] protocol-native.c: Client spotify changes volume of sink input
> *>* Spotify.
> *> >* whenever the application volume is changed. At the same time they are shown
> *>* I can hear cracklings. So it seems related. I noticed that forcing pulsesrc
> *>* to use lower latencies help but do not fix the problem. Changing volumes
> *>* with pulsesrc latency-time parameter set to 1000 us produces less noises
> *>* than when it is set to 10000 us.
> *> >* I tried my best to see if there is anything I can do on my side to remove
> *>* this noise I found nothing. Is that how things are or is there anything
> *>* that can be done to remove this noises?
> *
> This is how things are. It would be great if someone would have a hard
> look at the monitor source rewinding code and see what goes wrong
> there.
>
> Ok. Thank you for your answer Tanuk. For some reason it never got to my
email. I only noticed it because I have just opened the mailing list.
Strange.

Although a little annoying in my opinion this is not the end of the world.
The null sink reconfigure feature will be much more useful.

Best regards,

                  Wellington

-- 
Prof.° Wellington Wallace Miguel Melo

CEFET/RJ Uned Nova Iguaçu
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